Motor Control Flashcards
Define motor control
Motor control is the subdiscipline of human movement studies concerned with understanding the processes that are responsible for the acquisition, performance and retention of motor skills.
Define motor development
Deals with motor changes throughout the life span, specifically the changes in the acquisition, performance, and retention of motor skills that occur with growth, development, maturation and ageing.
Define motor learning
Deals with motor control changes that occur as a consequence of practice (or adaption), focusing literally on how motor skills are learned and the changes in performance, retention, and control mechanisms that accompany skill acquisition.
Other terms used to define motor control?
Motor behaviour Psychology of motor behaviour Motor learning and control Skill acquisition
What does motor mean?
Movement
What are motor skills?
Goal-directed actions that require movement of the whole body, limb, or muscle in order to be successfully performed
What imaging techniques to physiologists use?
Magneic resonance imaging (mri) and positron emission tomography (pet scan)
What equipment for physiologists use for measuring electrical activity in the brain?
Electroencephalography and magneto-encephalopathy
What equipment for physiologists use for measuring electrical activity in the muscles?
Electromyography
What are the neurological receivers?
Receptors
What are the effectors in the body?
Muscles
What is plasticity?
In the central nervous system, as in the communication network, it is the capacity for constant change
How many neurons are there in the CNS?
Between 10^12 to 10^14 neurones
How many (up to) synaptic connections with other neurons/receptors/motor units can neurons have?
Up to 10^4
Two major subdivisions of the nervous system?
Central nervous system (CNS) Peripheral nervous system (PNS)
What does the CNS consist of?
The brain and the spinal cord, responsible for overseeing and monitoring the activation of all sectors of the body, including muscles
What does the PNS do?
Carries information from the sensory receptors to the central nervous system and commands from the central nervous system to the muscles.
Two sensory outputs of the PNS?
Afferent and efferent
Latin definition of afferent?
To carry forward
Latin definition of efferent?
To carry away
What does the cell body of a nerve do?
Containing the nucleus, regulates the homeostasis of the neuron
What do dendrites do?
Collectively formed in a dendritic tree, connect with and receive information from other neurons, and in some cases, sensory receptors
What does the axom do?
Responsible for sending information away from the neuron to other neurons
What do the alpha motor neurons of the spinal cord do?
They possess many dendritic branches and a relatively long axon, also heavily branched to innervate multiple (100-15k) skeletal muscle fibres
What do gamma motor neurons do?
They are innervate contractile (intrafusal) fibres located in the muscle receptors. Consequently, they have considerably less-branched axons than do alpha motor neurones. Also located in the spinal cord.
What percentage of neurons in the spinal cord are gamma?
40%
What are pyramidal cells?
Located in the motor cortex of the brain; they funnel down to a single slender axom. Pyramidal cells send motor commands over the long distances from the brain to the spinal cord and may have axoms up to 1m in length.
Where are purkinje cells found?
In the cerebellum
What are Purkinje cells?
Single thin axom to which information is sent from an incredibly rich, systematically organised set of dendrites that provide these neurons with a characteristic tree-like appearance
What are interneurons?
A variety of shapes but typically have multiple dendrites and branching axoms that permit the connection of multiple neurons with multiple neurons
Where are interneurons formed and terminated?
Either in the brain and spinal cord
What are all neurons in the CNS surrounded by?
Other cells called glia or glial cells
What do glia/glial cells do?
They provide, among other things, the metabolic and immunological support for neurons
How do neurons carry messages?
From their dendrites to the terminal fibres of their axoms through a series of electrical pulses that are produced in the axom hillock
What does the electrical pulse produced by the axon hillock dependant on?
The sptial and temporal distribution of the pulses impinging on the cell body from its denritic tree
How to signals differentiate in weight in the neurons?
Signals arriving early and originating from dendrites close to the axon hillock carry more weight than do signals from distant neurons arriving late.
How does an axon hillock trigger a pulse?
When the summed weight of impulses reaching the neuron exceeds its threshold voltage
Where does a pulse of an axom hillock propagate to?
Along the axon to its terminus
What is myelin?
Fatty substances surrounding axoms
How do neurons pass information from one neuron to another?
Via Synapses
What does the greek original word for synapse mean?
Union
What is the gap between the presynaptic neuron and the postsynaptic neuron?
The synpatic cleft or junction
How does the electrical activity between neurons transmit?
Either by the direct spread of electrical current, or more frequently, the action of a chemical mediator called NEUROTRANSMITTER
What is acetycholine? (ACh)
A type of neurotransmitter (best known)
What is proprioception?
Information about the movement and orientation of the body and body parts in space
How is proprioception sensed?
Via kinesthetic receptors and vestibular receptors
What does the work kinesthesis derived from?
Move and sensation
What is the word proprioreception derived from?
Own
Where are kinesethic receptors?
Kinesthetic receptors are located in the muscles, tendons, joints and skin
Where are vestibular receptors located?
In the inner ear
What do vestibular receptors aid with?
Balance
What is acuity?
The highest level of visual sensitivity
Where is the highest density of photoreceptors?
The voea
Where do the majority of our optic nerves link between?
Areas of the midbrain (lateral geniculate nucleus) and the visual cortex (in the cerebrum)
Aside from the visual cortex and midbrain, where do the remaining optic nerves lie?
The superior colliculi (in the midbrain)
What do the nerves in the superior colliculi provide?
Ambient vision
What does focal vision do?
Specialised for recognising objects, distinguishing detail and assisting in the direct visual control of fine, precise movements (such as threading a needle)
What does ambient vision do?
Receives information from the whole of the retina, including the peripheral retina, and is concerned with the location of moving objects in the whole visual field. This pathway is especially implicated. Tion in sp and our rate of movement through the environment.
What does damage to the focal vision pathway ensue?
The inability to identify objects but the ability to located
What does damage to the ambient vision do?
Inability to locate objects though still have the ability to identify them
What is the principal source of sensory information from skeletal muscle?
Muscle spindle (a type of receptor)
Where would you find the most muscle spindles?
In the hand (fine motor control)
What are the two types of large muscle fibres in muscle spindles?
Extrafusal muscle fibres and intrafusal muscle fibres
How do intrafusal fibres differ from extrafusal fibres?
They are smaller (and incapable of directly causing whole muscle contraction) They are NOT innervated by alpha motor neurons but independently by gamma motor neurons (activity from brain not spine) When stimulated, contract only at endpoints, not whole length Have sensory receptors located along them and afferent connections back to the spinal cord
What are the receptors in tendons called?
Golgi tendon organs
What type of sensory output do golgi tendon organs emute?
Type 1b afferent fibres
What are some receptors on the skin?
Meissner’s corpuscles and Merkel’s discs
What are receptors wrapped around hair follicles?
Ruffini corpuscles
What receptors are located deeper in the skin and respond mostly to deep compression and high frequency vibrations?
Pacinian corpuscles
What are skin receptors called?
Cutaneous receptors
Three types of joint receptors?
Modified Ruffini Corpuscles, modified Pacinian ropuscles and Golgi Organs
Two types of versitular apparatus receptors?
The semicircular canals (superior, horizontal and posterior canals) Otilith Organs (the utricle and the saccule)
What does the semicircular canal respond to?
Angular acceleration in the three planes
What do the otolith organs respond to?
Linear acceleration
What is the size principle?
In natural movement, motor units are typically recruited in order of size; the motor units containing the smaller, less-forceful muscle fibres are recruited first. The order of activation is the size principle.
What are reflex movements?
Rapid movements occurring below the level of conciousness
Two main functions of the spinal cord?
Carries both input and output information from the sensory receptors to the brain and back to the muscles To support reflexes at the local spinal level to provide rapid, essentially automatic responding to noxious stimuli and to ensure the successful execution of movements already underway
How many spinal nerves are attached to the spine?
31
What part of the spinal nerve carries the efferent information?
The anterior (or ventral) root
What part of the spine carries afferent information?
The posterior (or dorsal) root
What does the anterior root comprise of?
Almost exclusively axons of alpha motor neurons, the cell bodies of which are located in the ventral horn
What is the posterior root comprised of?
Both the axons of the sensory neurons and their cell bodies, the latter clustered together to form the dorsal root ganglion